The generally accepted time and temperature conditions which define when a food product is fully cooked is an internal temperature of the food product of at least 160 degrees Fahrenheit. Upon reaching this internal temperature, it has been determined that virtually all bacterial pathogens in the food product are rendered non-pathogenic. Because meat and poultry food products are predominantly water, if internal temperatures of food product of at least 160 degrees Fahrenheit are achieved rapidly such as through frying, broiling or grilling, moisture is driven from the food product. As a result, the food product is rendered dry, tasteless and generally unappealing. While raising the temperature of the food product slowly results in the lowest dissipation of moisture, such extended cooking is not possible in many restaurants, particularly fast food restaurants. Hence, processors of meat and poultry products, such as deboned chicken or ground beef meat patties, deliver such products to restaurants in frozen but precooked states. That is, the internal temperature of the product was raised to at least 160 degrees Fahrenheit at the food processing facility. Cooking time at a restaurant is therefore reduced as the frozen food product need only be thawed and warmed to a palatable temperature.
To effect gradual cooking of the food product to minimize water loss, food processors have utilized horizontally oriented linear cookers or vertically oriented spiral steam cookers. Spiral steam cookers are often preferred due to lesser floor space requirements. Because of their configuration, spiral steam cookers provide extended exposure of the food product to boiling water temperatures to gradually elevate internal temperatures of the food product. Examples of spiral steam cookers are seen in U.S. Pat. Nos. 4,363,263; 4,582,047 and 4,737,373. The steam temperature and thus the cooking chamber in such prior art spiral steam cookers is maintained at a constant, typically from at least 160 to about 212 degrees Fahrenheit.
A problem with these and other prior art spiral steam cookers and related cooking methods is the inability to reach a uniform internal product temperature and the extended time required for raising the internal temperature of the food product to the required temperature of 160-185 degrees Fahrenheit. Such extended cooking times prevents high rates of production of cooked food product.
In addition, where steam temperatures in prior art cookers are elevated, they are often too high to optimize the desirable moisture content of the food product and are not uniform throughout the cavity of the cooker. However, a reduction in steam temperature to maximize moisture content would further prolong cooking times.
Hence, prior to the present invention, a need existed for a spiral conduction vapor cooker and related cooking method which results in higher rates of heat transfer production of cooked food product yet utilizes reduced conduction and vapor temperatures to preserve the maximum moisture content of the food product by precise internal, equilibration temperature in the center of the product.